The four-color FISH probes for 6p25 (RREB1-Ras responsive element-binding protein-1), 6q23 (MYB-myeloblastosis), 11q13 (CCND1,cyclin-D1 or chromosome 11q), and CEP6 (a centromeric reference point on chromosome 6) distinguished melanoma and benign melanocytic lesions according to variation in copy number of the genes, usually gain. Here, RREB1 is linked to melanoma.